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Thresholdless Laser Based on Photonic Time Crystals

Ke Xu, Ming Fang, Jian min Feng, Chenran Liu, Kaikun Niu, Guoda Xie, Zhixiang Huang

Published Jun 26, 2023• 2 citations
Publisher

Abstract

Abstract We present an electrodynamic model for thresholdless lasers based on the utilization of photonic time crystals (PTCs). By incorporating the unique physical properties of PTCs and employing a comprehensive four-level system model, we demonstrate the feasibility of achieving thresholdless laser operation. The proposed electrodynamic model captures the intricate interplay between the electromagnetic field and the PTC medium. We account for the ultrafast periodic variations in the refractive index of the PTCs, which are a result of their time crystal-like behavior. The model considers the dynamic response of the four-level system, taking into account the population inversion and relaxation processes. Through our electrodynamic modeling, we elucidate the underlying mechanisms that enable thresholdless laser operation in PTC-based systems. We demonstrate that the ultrafast refractive index variations lead to a self-sustaining laser action, eliminating the need for a lasing threshold. Moreover, we investigate the influence of various parameters, such as pump power and modulation period, on the laser performance and output characteristics. The electrodynamic model developed in this study provides a comprehensive framework for understanding and designing thresholdless lasers based on photonic time crystals. Our work contributes to the advancement of thresholdless laser technology and paves the way for potential applications in areas such as optical communications, sensing, and quantum photonics.

DOI
10.21203/rs.3.rs-3085133/v1

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Abstract We present an electrodynamic model for thresholdless lasers based on the utilization of photonic time crystals (PTCs). By incorporating the unique physical properties of PTCs and employing a comprehensive four-level system model, we demonstrate the feasibility of achieving thresholdless laser operation. The proposed electrodynamic model captures the intricate interplay between the electromagnetic field and the PTC medium. We account for the ultrafast periodic variations in the refractive index of the PTCs, which are a result of their time crystal-like behavior. The model considers the dynamic response of the four-level system, taking into account the population inversion and relaxation processes. Through our electrodynamic modeling, we elucidate the underlying mechanisms that enable thresholdless laser operation in PTC-based systems. We demonstrate that the ultrafast refractive index variations lead to a self-sustaining laser action, eliminating the need for a lasing threshold. Moreover, we investigate the influence of various parameters, such as pump power and modulation period, on the laser performance and output characteristics. The electrodynamic model developed in this study provides a comprehensive framework for understanding and designing thresholdless lasers based on photonic time crystals. Our work contributes to the advancement of thresholdless laser technology and paves the way for potential applications in areas such as optical communications, sensing, and quantum photonics.
An electrodynamic model is presented in this Letter to describe thresholdless lasers, utilizing the application of photonic time crystals (PTCs). By integrating the distinctive physical properties of PTCs and employing a comprehensive model based on a four-level system, the feasibility of achieving thresholdless laser operation is demonstrated. The proposed electrodynamic model comprehensively captures the intricate interplay between the electromagnetic field and the PTC medium. The model takes into account the ultrafast periodic variations in the refractive index of the PTCs, which arise from their time crystal-like behavior. Additionally, the dynamic response of the four-level system is considered, factoring in the processes of population inversion and relaxation. This Letter seeks to elucidate the underlying mechanisms that facilitate thresholdless laser operation in PTC-based systems. Through our electrodynamic modeling approach, we demonstrate that the ultrafast variations in the refractive index of PTCs give rise to a self-sustaining laser action, obviating the need for a lasing threshold. Moreover, we investigate the impact of various parameters, including pump power and modulation period, on the laser's performance and output characteristics. The developed electrodynamic model provides a comprehensive framework for comprehending and designing thresholdless lasers based on photonic time crystals. This research contributes to the advancement of thresholdless laser technology and opens up possibilities for applications in optical communications, sensing, and quantum photonics.
The present study considers the operation of a laser that incorporates a photonic time crystal (PTC), the purpose of which is to generate a field characterised by multiple widely separated optical frequencies. This laser is the subject of both a proposal and theoretical investigation. The laser comprises an active medium and a PTC within a small cavity constructed from two photonic crystals that are positioned in an overlapping configuration. PTC is modulated by an external field. The spikes in the laser field spectrum are separated by the PTC modulation frequency. The development of a quantum model of the laser with PTC has been achieved, and the analysis of a lasing mode with multi-frequency spikes has been made. The investigation focused on the study of lasing conditions, output power, and the lasing field spectra. The experimental realization of the multi-frequency laser with PTC under realistic conditions is discussed.
In this Letter, a scheme for realizing an electromagnetic induced transparency (EIT) analog in the photonic time crystal (PTC) is proposed. Strategies for achieving EIT-like phenomena in PTCs are explored, the transmission matrix method is elaborated, and a time-domain multilayer configuration for EIT-like effects is presented. The EIT-like phenomenon in PTC is analyzed using coupled-mode theory, with phase shifts and group delays discussed to validate the accuracy of the EIT-like phenomenon. Research shows that increasing the modulation depth of the PTC by modulating the refractive index in a temporal slab can effectively enhance the intensity of the EIT-like effect. This provides a feasible technical pathway for realizing EIT-like effects in time-varying systems and lays the foundation for related applications such as slow light technology in the time domain.
Photonic quantum computing has been rapidly advancing over the past decade, with measurement-based approaches emerging as particularly promising. A crucial requirement for these approaches is the generation of large-scale cluster states. In this work, we present a method to create cluster states using Photonic Time Crystals (PTCs)—dielectric materials with their refractive index rapidly modulated in time. PTCs effectively function as a set of optical parametric oscillators and beam-splitters, producing simultaneous two-mode squeezing for many pairs of photonic modes with opposite wavevectors. We utilize this capability to propose a method for generating two-dimensional cluster states, offering important advantages over existing protocols.
We investigate superradiant lasing in 1D photonic crystal taking into account both homogeneous and inhomogeneous broadening in a two-level active medium. The latter may be based on, e.g., the quantum-well heterostructures and the fibers activated by color centers where Bragg structure can be fabricated artificially by means of a periodic modulation of the cladding layers. The truncated Maxwell-Bloch equations for the counter-propagating waves, the polarization and inversion of an inhomogeneously broadened two-level medium are used to analyze numerically the interplay between the back-scattering, amplification, dispersion, and de-phasing of waves. It is found that, if the photonic band gap is less than the coherent amplification bandwidth, there is a wide range of the pumping and relaxation parameters of a two-level medium where superradiant lasing exists and results in generation of a quasi-periodic and/or chaotic series of powerful and short pulses similar to those of Dicke superfluorescence. It is the cavity mode selection due to distributed feedback caused by the resonant Bragg structure which is responsible for the existence of superradiant lasing. Typical parameters of superradiant photonic-crystal lasers, including lengths, photonic band gaps and relaxation rates, are indicated.
We demonstrate the capability of complete thresholdless lasing operation between dressed states of a two-level atom located inside a microscopic cavity engineered in a photonic band-gap material. We distinguish between threshold and thresholdless behaviors by analyzing Mandel's QQQ parameter for the cavity field. We find that the threshold behavior depends on whether the spontaneous emission is or is not present on the lasing transition. In the presence of the spontaneous emission, the mean photon number of the cavity field exhibits threshold behavior, indicating that the system may operate as an ordinary laser. When the spontaneous emission is eliminated on the lasing transition, no threshold is observed for all values of the pumping rate, indicating the system becomes a thresholdless laser. Moreover, we find that, under a thresholdless operation, the mean photon number can increase nonlinearly with the pumping rate, and this process is accompanied by a sub-Poissonian statistics of the field. This suggests that the nonclassical statistics can be used to distinguish a nonlinear operation of the dressed-atom laser.